This invention is directed toward the art of effectively operating variable air volume delivery systems, and particularly toward the control of static pressure in the supply ducts of said variable air volume delivery systems during the delivery of air irrespective of the amount of air delivered in such systems.
One example of a variable air volume delivery system includes rooftop air conditioners in the 20-100 ton operational range, which include extensive ductwork to the rooms and spaces subject to air delivery. Such air conditioners frequently face the problem of controlling static pressure in their ductwork during variable air volume applications, because of the need to continually modify the amounts and quantities of air needed to be delivered in order to establish effective building temperature control with regard to conditioned and conditionable rooms and spaces therein.
The problem of static pressure control can be usefully understood and illustrated by the following example. As the need for cooling a room or space to be conditioned decreases, the air terminals in the rooms and spaces addressed begin to modulate between open and closed states, to reduce the amount of air delivered to the region being conditioned. This of course increases the static pressure delivery by the blower of the variable air volume delivery system driving the air in direct relationship to the reduction in the amount of air delivered.
In other words, as the amount of air is reduced with diminished need, the system itself requires only a reduced level of static pressure. Instead, the level of static pressure is in fact increased, because less amounts of air are actually lost during operation under reduced air flow conditions.
Significantly, not only are static pressure levels at their maximum just when they are clearly least needed, but the excessive level of static pressure applied at repeated intervals can indeed increase energy costs and additionally cause damage to the ductwork of the air volume delivery system being operated and also to the room terminals delivering the air to the spaces being conditioned.
It would thus be advantageous to regulate, or reduce, the static pressures present during system operation for many reasons relating both to energy savings and to the structural integrity and mechanical maintenance of the system. Beyond that, it is of course clear that solving the static pressure problem indicated would tend to promote energy savings for the user and to reduce the work done by the air volume delivery system blower which bears in substantial part the burden of producing such excessive static pressure levels.